A dual direction transmission device of the prior art typically includes a dual direction selecting mechanism which is driven by a motor through a pulley and belt transmission. Two spindles are operatively connected with said dual direction selecting mechanism respectively. Thereby, either one of the spindles is subject to the direction of rotation of the motor, whereby the other spindle will be freely rotatable.
The dual direction transmission device of the prior art is defective in that the dual direction selecting mechanism must be mounted away from said two spindles, thereby occupying a non-negligible space.
In view of this, a primary object of the invention is to solve said defect, that is, the object of the invention is to change the structure of the dual direction selecting mechanism, whereby it may be mounted on those two spindles in order to minimize the space occupied thereby.